"Alias" and "Aliasing" are descriptive and used perfectly in the Modern Perl example to describe this behavior, but not what I had in mind.

By "fancy" I supposed I meant a large, and overly-complex-sounding single word that represented this specific behavior of auto-aliasing the iterator within a loop to allow in-place modifications of the thing being iterated on.

My memory might be completely wrong on this, maybe no such word exists. I sure can't find it. I just have this memory...of something... and it's been driving me crazy for a week. It's been about 10 years since I've logged into PerlMonks and this has driven me to dig up my password and login to ask! :)

pointer

Aliasing is the correct term, you might differentiate between

• loop aliasing ( foreach ) ,
• argument aliasing ( @_ ) and
• (explicit) symbol table aliasing (typeglobs)

, but that's hardly needed.

See perlglossary#alias for more.

Update

¹) Perl might be often magic but it's not a J.K.Rowling novel with "Gryffindor" loops. ;)

"...and modifying the iterator variable modifies the array that you are iterating through ..."

foreach my $a (@ar) ...

You are not using the "traditional" C style for loop. You are using the Perl style foreach loop. From perlsyn:

Big difference. You might be comparing apples to oranges here. Consider this code which actually changes the iterator variable instead of the element.

my @ar = (1, 2, 3);
for my $i (0 .. $#ar) {
  $i = $i + 1;
}

print join ", ", @ar; # prints 1, 2, 3
[download]

UPDATE:
I was attempting to point out that the OP mentioned "modifying the iterator variable" when they are actually modifying the "loop index variable" as perlsyn documents.

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)

Consider this code which actually changes the iterator variable instead of the element.

my @ar = (1, 2, 3);
for my $i (0 .. $#ar) {
  $i = $i + 1;
}


I understand you to be saying that in the quoted code, a change to $i does not affect the loop list element from which the value of $i is drawn, i.e, $i is not an alias.

But consider the failure of the following:

c:\@Work\Perl\monks>perl -wMstrict -le
"print 'runtime';
 for my $i (1, 2, 3) {
   $i = $i + 1;
   print $i;
   }
 print 'done';
"
runtime
Modification of a read-only value attempted at -e line 1.
[download]

I think that in both cases $i is being aliased to elements of an anonymous loop list.

In the first (quoted) case, the  (0 .. $#ar) expression creates a mutable anonymous list, the elements of which can be changed freely.

In the second case,  (1, 2, 3) creates an immutable loop list. In this case, the statement
    $i = $i + 1;
is equivalent to the meaningless statement
    1 = 1 + 1;
for the first element of the loop list because $i is aliased to a literal 1, and the interpreter throws up its hands.

---

Give a man a fish:  <%-(-(-(-<

He didn't say he was using a C-style for loop, did he?

Might you be trying to answer a question that no one asked?

"iteration by reference"?

No, I have no idea. I'd simply call it "aliasing" as well.